A “hybrid automatic repeat request” (HARQ) protocol may particularly denote a channel coding architecture for a communication system. In HARQ, a part of data (which had been transmitted properly) from an earlier transmission of a communication message may be combined with another part of data (which had not been transmitted properly previously) from a later re-transmission of the communication message. HARQ may be considered as a variation of an ARQ (automatic repeat request protocol) error control method. In ARQ, error-detection information (ED) bits may be added to data to be transmitted (such as cyclic redundancy check, CRC). In Hybrid ARQ, forward error correction (FEC) bits may also be added to the existing Error Detection (ED) bits (such as Reed-Solomon code or Turbo code). As a result, Hybrid ARQ performs properly even under poor signal conditions.
WO 2007/078219 is based on ARQ in wireless communication systems, wherein a coded message block is spread over a plurality of sub-carriers or components. WO 2007/078219 introduces an equalizing HARQ method. The equalizing HARQ identifies and re-transmits the most distorted parts of a received coded message block. In addition, the re-transmitted parts can optionally be relocated to components of higher quality, which ensures good re-transmission quality for those badly distorted parts in the prior transmission. After a soft-bit combination in a receiving node, the final received codeword experience an equalized quality variation with low multi-state performance loss.
Conventionally, HARQ technology may use a HARQ buffer with a challenging memory requirement.